An Exeter University society has apologised after provoking outrage when it printed a sick rape "joke" in a leaflet dubbed the "shag mag" to promote a safe sex student ball.

The joke estimated the number of calories a man could burn off by stripping a girl naked without her consent and has been described as "beyond ugly". It was part of a two-page spread which detailed the energy spent on sexual practices.

The booklet is given out with every ticket purchased by students for the Safer Sex Ball, run by Exeter's RAG society. The charity event is supposed to highlight the importance of using condoms but has raised concerns the ball instead promotes promiscuity. Party-goers, which can number in their thousands, adhere to a dress code where less is considered more and are handed free condoms by the society.

Sophie Odgers-Roe, the Guild's Racial Equality Representative, told University website Xmedia she was "horrified" by the joke.

She said: "When I saw it, I was shocked, horrified and outraged. I just can't believe the sheer audacity of it."

Roe is now campaigning for an independent examination of all publications before they are allowed to go to print, to avoid a repeat.

Yvonne Traynor, chief executive of the Rape Crisis support centre, said the joke should an "insensitive lack of intelligence by the author".

"It is appalling that in these times when one in four women is suffering from sexual violence a student has no grasp of the serious consequences of a statement like this. Perhaps we should ask how many calories a man could burn off each day in prison when they are convicted of attacking women", she told the Huffington Post.

"Someone should be accountable for initiating this statement and printing it and that person needs serious counselling!"

Students took to Twitter to condemn the joke, with one saying it was "incredibly insensitive".

Research pupil Natalie Garrett added it was "beyond ugly" and demanded: "What message are you trying to send to undergraduates? Lead by example."

A spokesperson for the university's students' guild said:

"RAG would like to apologise unreservedly for any offence caused by an unacceptable comment made in the magazine. RAG does not condone abuse in any way, shape or form and we’re deeply sorry that this was allowed to be published.

"In addition, the Students’ Guild would like to sincerely apologise for not picking this matter up at the proofing stage and for not removing it from publication. An investigation is underway, looking at how this happened and ensuring that nothing like this happens again.

"All copies of the magazine have been removed and new copies are being reprinted."